1. Field
The present invention relates to a robot and a method of building a map therefor, and more particularly to a robot, which builds a map using surface data of a three-dimensional image, from which a dynamic obstacle is removed, and a method of building a map therefor.
2. Description of the Related Art
In general, machines, which conduct motion similar to that of a human using an electric or magnetic action, are referred to as robots. Recently, robots have been applied to various fields due to development of sensors and controllers. For example, there are housekeeping robots in homes, service robots in public facilities, transfer robots in industrial sites, and worker supporting robots. In order to allow a robot to conduct autonomous motion, localization in that a self position is recognized without previous data regarding the surrounding environment and map-building in which a map is built from the data regarding the environment must be carried out simultaneously. It is referred to as simultaneous localization and map-building (SLAM) of a robot.
Japanese Patent Laid-Open Publication No. H10-160463 discloses one example of a SLAM method.
In the SLAM method disclosed in the above document, an omnidirectional visual sensor having view fields in all directions is loaded beforehand to a moving body (robot), and obtains an image, which is set as a time series standard pattern, around the moving body when the moving body moves on a specific route. When the moving body moves on an optional route, the image obtained by the omnidirectional visual sensor is compared with an image set as the predetermined standard pattern. At this time, if the two images coincide with each other, the image of the moving body is judged to be at a position related to the image of the standard pattern, and a map around the surrounding environment is built. Here, it needs to be determined that an obstacle located on the route of the moving body is a fixed object (static object) or a moving object (dynamic object). The reason is that map data must be prepared based on only static objects, from which dynamic objects (hereinafter, referred to as dynamic obstacles) are removed.
However, the conventional SLAM method cannot recognize a correct position of a moving body but presumes only an approximate position of the moving body, and thus has a limit of recognizing whether or not an obstacle located on a route of the moving body is a static object or a dynamic obstacle. For example, when the dynamic obstacle is recognized as a static object, map data prepared based on the static object are distorted, and thus the position of the moving body obtained based on the map data includes many errors. Further, when the dynamic obstacle is recognized as a static object, the moving body cannot avoid the dynamic obstacle and thus may cause a collision with the dynamic obstacle.